89 ... Disconnect knock sensor?
Thread Starter
Racer
Joined: Jan 2004
Posts: 300
Likes: 1
From: Wollongong NSW
89 ... Disconnect knock sensor?
here's the situation,
car ran strong through 1st,2nd and 3rd gears shifting about 6200 each time, when in 4th was on it until about 4500 then short shifted to 5th and got off the gas, after this a code 43 set and had a sudden loss in power and coughed and ran rough if i attempted to get on it again
( i presume it went into limp mode). Stopped car and reset, drove around with car strong again and repeated the scenario and same thing happened.
QUESTION is: could this be a false knock from the long tube headers only at a certain frequency and RPM and only while de-accelerating? because if it was real knock it should occur while on it at 6000 and not when backing off.
Has anyone with an 89 disconnected there knock sensor without causing more codes?
Has anyone disconnected there ESC module and what was the result?
Thanks to all
car ran strong through 1st,2nd and 3rd gears shifting about 6200 each time, when in 4th was on it until about 4500 then short shifted to 5th and got off the gas, after this a code 43 set and had a sudden loss in power and coughed and ran rough if i attempted to get on it again
( i presume it went into limp mode). Stopped car and reset, drove around with car strong again and repeated the scenario and same thing happened.
QUESTION is: could this be a false knock from the long tube headers only at a certain frequency and RPM and only while de-accelerating? because if it was real knock it should occur while on it at 6000 and not when backing off.
Has anyone with an 89 disconnected there knock sensor without causing more codes?
Has anyone disconnected there ESC module and what was the result?
Thanks to all
Instructor
Joined: Sep 2005
Posts: 107
Likes: 0
From: Arizona
Keep it connected. It allows precise timing advance by the ECM. If you disconnect the ESC, the engine operate roughly. Do what I did, have a custom chip burnt, and specify to have your knock sensor desensitized. Not deactivated, but less sensitive. It worked for me. Speak with Alvin @ pcmforless.com to further research your problem. Good luck.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
Read this material on 65Z01's site
'How to Stop False Knock Counts in '85-'89 L98'
Also. Instead of guessing, consider getting a cable,
some software and then log your runs. This way you
can better see what is happening and when. Maybe
even why it is happening.
You would need to take this step anyway to make the
most of getting a tune from 'PCM for Less' or others.
.
'How to Stop False Knock Counts in '85-'89 L98'
Also. Instead of guessing, consider getting a cable,
some software and then log your runs. This way you
can better see what is happening and when. Maybe
even why it is happening.
You would need to take this step anyway to make the
most of getting a tune from 'PCM for Less' or others.
.
Thread Starter
Racer
Joined: Jan 2004
Posts: 300
Likes: 1
From: Wollongong NSW
Thanks for the replies, but with auto xray, false knocks caused by other noises or true knock show up as the same, and am getting virtually no knock counts at high rpm when accellerating, but some counts when i do as previously posted. That is why i thought it must be header noise causing the problem. Will definately try the less sensitive esc module and see if that helps.
Anyone else got suggestions?
Anyone else got suggestions?
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Think about what is happening here. When knock is sensed, the timing is retarded to protect the engine. The ESC can't tell the difference between true and false knock. That is why false knock is such a problem. BUT, retarding the timing is "business as usual". When knock is sensed, that is what it was designed to, and is supposed to, do. A light shouldn't flash and a code shouldn't be set. The "Check Engine" or "Service Engine Soon" light illuminates when there is a problem in the system. Code 43 indicates a malfunction in the ESC circuit... Not that the circuit functions.
First trouble shoot and repair the ESC, as per your FSM and THEN you can go after the sources of false knock... If there really IS any.
RACE ON!!!
First trouble shoot and repair the ESC, as per your FSM and THEN you can go after the sources of false knock... If there really IS any.
RACE ON!!!
Thread Starter
Racer
Joined: Jan 2004
Posts: 300
Likes: 1
From: Wollongong NSW
Originally Posted by CFI-EFI
Think about what is happening here. When knock is sensed, the timing is retarded to protect the engine. The ESC can't tell the difference between true and false knock. That is why false knock is such a problem. BUT, retarding the timing is "business as usual". When knock is sensed, that is what it was designed to, and is supposed to, do. A light shouldn't flash and a code shouldn't be set. The "Check Engine" or "Service Engine Soon" light illuminates when there is a problem in the system. Code 43 indicates a malfunction in the ESC circuit... Not that the circuit functions.
First trouble shoot and repair the ESC, as per your FSM and THEN you can go after the sources of false knock... If there really IS any.
RACE ON!!!
First trouble shoot and repair the ESC, as per your FSM and THEN you can go after the sources of false knock... If there really IS any.
RACE ON!!!
I agree with this comment entirely but forgot to mention i have checked the esc according to my helms and it checks out ok, which is why i came to the conclusion it could be false knock from header noise on de-accelleration as my helms states that a code 43 will set if knock exists for 4secs or more, and the header noise on de-cel lasts for more than 4secs and seems rougher and louder than normal.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Your Helms and ESC circuits are different than mine. For instance, I have had my knock sensor disconnected for over 5 years...no light, no code. I don't think you can do that with your later car. First, I would determine if I really was the "victim" of false knock. I was. I checked, back before I disconnected my knock sensor and the out come was the reason why I did. Once you determine if you are getting it, you can decide the best way to deal with it.
RACE ON!!!
RACE ON!!!
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Drifting
Joined: Jan 2002
Posts: 1,606
Likes: 1
From: Las Cruces NM
I think the helms is off on that one. I had a piston fail and it was knocking pretty bad. While t/s, I noticed the knock counts would jump 20 counts or so everytime that piston fired. Once the counts reached a certain amount, the count reset. No got was set at all.
